Process for the preparation of malononitrile

Abstract

A novel process for the preparation of malononitrile which involves subjecting a (2-cyano-N-alkoxy)acetimidoyl halide to a high-temperature treatment.

What is claimed is: 
     
       1. A process for the preparation of malononitrile, characterized in that a (2-cyano -N-alkoxy )acetimidoyl halide of the formula: ##STR5## in which R 1  and R 2  are identical or different and are hydrogen or alkyl, R 3  is alkyl, cycloalkyl, aryl, arylalkyl or a group: ##STR6## in which R 4  is an alkyl, aryl or arylalkyl group, and X is a halogen atom, is converted into malononitrile by a temperature of from 500° to 1000° C. 
     
     
       2. The process according to claim 1, wherein the conversion is carried out at a temperature of 700° to 1000° C. 
     
     
       3. The process according to claim 2, wherein the (2-cyano-N-alkoxy)acetimidoyl halide of the formula I is prepared by halogenation of a (2-cyano-N-alkoxy)acetamide of the formula: ##STR7## in which R 1  is as defined above. 
     
     
       4. The process according to claim 3, wherein the halogenation is a chlorination and is carried out using phosphorus pentachloride, phosphene, phosphorus oxychloride or tetrachloromethane in conjunction with triphenylphosphine. 
     
     
       5. The process according to claim 4, wherein the halogenation is carried out in the presence of a halogenated solvent at a reaction temperature of from -20° to 150° C. 
     
     
       6. The process according to claim 3, wherein the halogenation is carried out in the presence of a halogenated solvent at a reaction temperature of from -20° to 150° C. 
     
     
       7. The process according to claim 1, wherein the (2-cyano-N-alkoxy)acetimidoyl halide of the formula I is prepared by halogenation of a (2-cyano-N-alkoxy)acetamide of the formula: ##STR8## in which R 1  is as defined above. 
     
     
       8. (2-Cyano-N-alkoxy)acetimidoyl halide of the formula: ##STR9## in which R 1  and R 2  are identical or different and are hydrogen or alkyl, R 3  is alkyl, cycloalkyl, aryl, arylalkyl or a group: ##STR10## in which R 4  is an alkyl, aryl or arylalkyl group, and X is a halogen atom.